The invention disclosed and claimed herein deals with high temperature ceramic intermittently sealable refractory tile and controlled air continuous gasifiers (rotary kilns) that are manufactured using such refractory tile, and waste to energy systems that have such gasifiers as part of the system.
The refractory tile and the novel controlled air continuous gasifiers of this invention form part of a system that is novel and environmentally effective to directly convert the latent thermal energy of biomass waste to power (electricity or steam) without the need for costly processes to clean contaminated flue gases.
A rotary kiln is essentially a slow moving, i.e. rotating, refractory-lined steel cylinder. To facilitate the movement of waste material, it generally slants downward from the feed end to the outlet end. The kiln is heated to high temperatures and as material passes through the kiln, waste is evaporated, organic materials are volatized and combustion begins. Generally, rotary kilns can be designed to operate at temperatures between 1400 and 2600 degrees Fahrenheit. The kiln""s end product can be either ash or slag, depending on the mode of operation and the initial characteristics of the waste that is fed to the kiln.
Key elements of rotary kiln design are the end seals, drive assembly, kiln refractory and control systems. The end seals are designed to minimize leakage of air into the system and prevent escape of combustion gases. The drive assembly must supply enough torque to rotate the kiln under all operating conditions. The refractory lining (tile) protects the kiln shell from overheating and chemical attack. At the same time, it provides a hot surface to aid in ignition and combustion of waste. Refractory surfaces near the feed inlet are designed for resistance to high impact and thermal shock loads. In the discharge area, refractory must withstand chemical attack and slag penetration.
In the inventive system disclosed and claimed herein using a rotary kiln of this invention, contaminated flue gas from waste combustion is used to heat clean air indirectly in a ceramic heat exchanger to temperatures up to about 2000 degrees Fahrenheit and clean air side pressures up to about 200 psig to run a gas turbine. No flue gas treatment is required, and the gas turbine can discharge clean air for process use rather than combustion products. The novel refractory tiles of this invention allow for the processing of waste without slag buildup and thus this invention eliminates one of the major problems associated with prior art kilns.
The invention herein destroys biomass and related wastes at their source and produces electrical power more efficiently than can be accomplished with conventional steam power plants. The system has low leakage in the heat exchangers used therein, and turbine efficiencies are high owing to the use of controlled maintenance air instead of combustion products.
Plants using the systems disclosed herein can be sized to handle large volume, low heat release, wet materials, at the source, to reduce trucking, storage, and related material handling situations. This process makes it possible for remote communities and industries to destroy municipal solid waste, sludge, wood products and trash and at the same time, generate electricity by firing a gas turbine with clean air.
The invention claimed herein deals with high temperature ceramic intermittently sealable refractory tile and controlled air continuous gasifiers that are manufactured using such refractory tile, and waste to energy systems that have such gasifiers as part of the system.
Thus, this invention deals in one embodiment with a ceramic ball seal refractory tile comprising a tile and contained within the tile is an air shaft, wherein the air shaft has contained in its interior a ceramic ball which can act as a seal for the air shaft.
This invention also deals with another embodiment which is a ceramic cap sealable refractory tile comprising a refractory tile and contained within said refractory tile, an air shaft having a near end, wherein the air shaft has a cap sealing mechanism mounted on the outside of the near end, which cap sealing mechanism acts as an intermittent seal for the air shaft.
A further embodiment of this invention is a ceramic cap sealable refractory tile comprising a refractory tile and contained within said refractory tile, an air shaft having a near end, wherein the air shaft has a cap sealing mechanism mounted on the outside of the near end, which cap sealing mechanism has associated with it a needle valve arrangement.
Yet another embodiment of this invention is a ceramic needle valve refractory tile comprising a tile and contained within the tile is an air shaft, wherein the air shaft has contained in its interior a ceramic needle valve which can act as a seal for the air shaft.
More specifically, this invention deals in one embodiment with a ceramic ball seal refractory tile comprising a ceramic refractory tile, an air shaft, a ceramic ball and, a delivery notch for air delivery, wherein the refractory tile is a high temperature ceramic refractory tile having a top, a bottom, a front and a back. The ceramic refractory tile has contained in it an air shaft which comprises an essentially vertical segment opening through the bottom of the refractory tile. The vertical segment has a bottom edge and the vertical segment has a generally cylindrical configuration. There is also present a flared, essentially horizontal segment opening through the back of the refractory tile and near the top of the refractory tile.
In addition, there is a non-vertical segment which provides a continuous conduit from the vertical segment to the horizontal segment. The non-vertical segment has a top half and a bottom half wherein the top half is flared and the bottom half is cylindrical.
The air shaft has a reduced neck at about the connecting point of the horizontal segment and the non-vertical segment to form a constriction in the air shaft which constriction provides for retaining the ceramic ball such that the ceramic ball can seat in said constriction to prevent the flow of air through the air shaft.
The delivery notch is located in the top of the refractory tile, at the front of the refractory tile. The depth of the delivery notch is deeper at the front, the depth being deeper than the exit point of the horizontal segment at the back of the refractory tile and the width of the delivery notch at the front of the refractory tile is at least as wide as the flare of the horizontal segment at the back of the refractory tile.
A variation of the sealing means described just supra is the substitution of the cap sealing mechanism mounted on the outside of the near end of the air shaft in place of the ball seal.
Such cap sealing mechanisms are used in conjunction with any of the ball or plug sealing mechanisms described herein. Such cap sealing mechanisms can be set for an angle of closure depending on several factors, for example the angle of repose of the waste inside. Such settings can be anticipated and calculated and the cap sealing mechanism preset for a given biomass.
Another variation of the sealing means described just supra is the substitution of a cap needle valve and, the needle valve in the air shaft.
It is contemplated within the scope of this invention to use other air control mechanisms to control the flow of air through the air shaft to provide the benefits set forth herein.
Another embodiment of this invention is a controlled air continuous gasifier containing a plurality of the refractory tile as described supra, it being understood that the continuous gasifier can use any of the air control mechanisms described herein, and can have a combination of such refractory tile.
More specifically, in one embodiment, the controlled air, continuous gasifier, comprises (i) a cylinder having a feed end and a product end and (ii) a feed end cap on the feed end of the cylinder. In addition, there is present, (iii) a product end cap on the product end of the cylinder and (iv) a product exit port in the product end cap. There is (v) a flue gas exit port in the feed end cap along with (vi) a waste feed port.
There is (vii), at least one air injection port near the product end cap, at least one air exit port (vii) near the feed end cap and at least one air exit port (viii) near the feed end cap in addition to a means (ix) for allowing rotation of the gasifier.
The cylinder comprises a refractory lined open center core running essentially the full length of the cylinder, wherein the refractory lining has an inside surface and an outside surface. There is a first metal shell covering the entire outside surface of the refractory lining, and the first metal shell has an outside surface as well.
There is an insulated second metal shell formed adjacent to, and conforming to, the outside surface configuration of the first metal shell such that there is a hollow core provided between the first metal shell and the second metal shell.
The refractory lining is as described supra, and is a ceramic refractory tile comprising a ceramic refractory tile, an air shaft, a ceramic ball, or ceramic needle, and, a delivery notch, wherein the refractory tile is a high temperature ceramic refractory tile having a top, a bottom, a front and a back. The ceramic refractory tile has contained in it, an air shaft, which air shaft comprises an essentially vertical segment opening through the bottom of the refractory tile. The vertical segment has a bottom and the vertical segment has a generally cylindrical configuration.
There is a flared, essentially horizontal segment opening through the back of the refractory tile and near the top of the refractory tile and a non-vertical segment providing a continuous conduit from the vertical segment to the horizontal segment.
The non-vertical segment has a top half and a bottom half wherein the top half is flared and the bottom half is cylindrical. The air shaft has a reduced neck at about the connecting point of the vertical segment and the non-vertical segment to form a constriction in the air shaft which constriction provides for retaining the ceramic ball or ceramic needle such that the ceramic ball or ceramic needle can seat in the constriction to prevent the flow of air through the air shaft.
The delivery notch is located in the top of the refractory tile, at the front of the refractory tile, the depth of said notch at the front of the refractory tile being deeper than the exit point of (ii) at the back of the refractory tile. The width of the notch at the front of the refractory tile is at least as wide as the flare of the horizontal segment at the back of the refractory tile.
There is still a further embodiment of this invention which is a waste to energy system comprising in combination at least the following: a. a gasifier of this invention; b. an oxidizer; c. an air-to-air, all-ceramic heat exchanger; d. a gas turbine; e. a generator operating from the gas turbine; f. a filter and compressor driven by the gas turbine.
It is further contemplated within the scope of this invention to add other elements to the system, depending on the location of the plant, the type of waste being processed, the availability of auxiliary fuel, and other such factors. For example, there can be added a high pressure, medium temperature, alloy metal air-to-air heat exchanger to the combination set forth just above. Other equipment is that equipment which is standard in the industry and can be, for example, waste feeders, shredders, and grinders; ash collectors and conveyors, other secondary combustion chambers; particle removers and filters; evaporators; acid scrubbers; boilers and economizers; steam generation and handling equipment; fans; stacks and chimneys; air handling equipment; means and methods of rotating the gasifier, and, means and methods of controlling all of such equipment.
It is contemplated within the scope of this invention to use auxiliary fuel supplies for firing the gasifier, firing the secondary combustion chambers, other equipment requiring such additional fueling, or any combination of them in the system.